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Showing papers on "Communications protocol published in 2009"


Proceedings ArticleDOI
16 Aug 2009
TL;DR: Through the design and implementation of PortLand, a scalable, fault tolerant layer 2 routing and forwarding protocol for data center environments, it is shown that PortLand holds promise for supporting a ``plug-and-play" large-scale, data center network.
Abstract: This paper considers the requirements for a scalable, easily manageable, fault-tolerant, and efficient data center network fabric. Trends in multi-core processors, end-host virtualization, and commodities of scale are pointing to future single-site data centers with millions of virtual end points. Existing layer 2 and layer 3 network protocols face some combination of limitations in such a setting: lack of scalability, difficult management, inflexible communication, or limited support for virtual machine migration. To some extent, these limitations may be inherent for Ethernet/IP style protocols when trying to support arbitrary topologies. We observe that data center networks are often managed as a single logical network fabric with a known baseline topology and growth model. We leverage this observation in the design and implementation of PortLand, a scalable, fault tolerant layer 2 routing and forwarding protocol for data center environments. Through our implementation and evaluation, we show that PortLand holds promise for supporting a ``plug-and-play" large-scale, data center network.

1,238 citations


Journal ArticleDOI
TL;DR: This work applies a classification technique to IVC applications to provide a taxonomy for detailed study of their communication requirements, and divides them into type classes which share common communication organization and performance requirements.
Abstract: Inter-vehicle communication (IVC) protocols have the potential to increase the safety, efficiency, and convenience of transportation systems involving planes, trains, automobiles, and robots. The applications targeted include peer-to-peer networks for web surfing, coordinated braking, runway incursion prevention, adaptive traffic control, vehicle formations, and many others. The diversity of the applications and their potential communication protocols has challenged a systematic literature survey. We apply a classification technique to IVC applications to provide a taxonomy for detailed study of their communication requirements. The applications are divided into type classes which share common communication organization and performance requirements. IVC protocols are surveyed separately and their fundamental characteristics are revealed. The protocol characteristics are then used to determine the relevance of specific protocols to specific types of IVC applications.

475 citations


Journal ArticleDOI
TL;DR: An overview of recent medium access control, routing, transport, and cross-layer networking protocols for underwater wireless applications is provided.
Abstract: Underwater wireless communications can enable many scientific, environmental, commercial, safety, and military applications. Wireless signal transmission is also crucial to remotely control instruments in ocean observatories and to enable coordination of swarms of autonomous underwater vehicles and robots, which will play the role of mobile nodes in future ocean observation networks by virtue of their flexibility and reconfigurability. To make underwater applications viable, efficient communication protocols among underwater devices, which are based on acoustic wireless technology for distances over one hundred meters, must be enabled because of the high attenuation and scattering that affect radio and optical waves, respectively. The unique characteristics of an underwater acoustic channel - such as very limited and distance-dependent bandwidth, high propagation delays, and time-varying multipath and fading - require new, efficient and reliable communication protocols to network multiple devices, either static or mobile, potentially over multiple hops. In this article, we provide an overview of recent medium access control, routing, transport, and cross-layer networking protocols.

377 citations


Proceedings ArticleDOI
17 May 2009
TL;DR: This paper presents a system that is capable of automatically inferring state machines, and introduces techniques for identifying and clustering different types of messages not only based on their structure, but also according to the impact of each message on server behavior.
Abstract: Protocol reverse engineering is the process of extracting application-level specifications for network protocols. Such specifications are very useful in a number of security-related contexts, for example, to perform deep packet inspection and black-box fuzzing, or to quickly understand custom botnet command and control (C\&C) channels.Since manual reverse engineering is a time-consuming and tedious process, a number of systems have been proposed that aim to automate this task. These systems either analyze network traffic directly or monitor the execution of the application that receives the protocol messages. While previous systems show that precise message formats can be extracted automatically, they do not provide a protocol specification.The reason is that they do not reverse engineer the protocol state machine.In this paper, we focus on closing this gap by presenting a system that is capable of automatically inferring state machines. This greatly enhances the results of automatic protocol reverse engineering, while further reducing the need for human interaction. We extend previous work that focuses on behavior-based message format extraction,and introduce techniques for identifying and clustering different types of messages not only based on their structure, but also according to the impact of each message on server behavior.Moreover, we present an algorithm for extracting the state machine.We have applied our techniques to a number of real-world protocols, including the command and control protocol used by a malicious bot. Our results demonstrate that we are able to extract format specifications for different types of messages and meaningful protocol state machines. We use these protocol specifications to automatically generate input for a stateful fuzzer,allowing us to discover security vulnerabilities in real-world applications.

276 citations


Journal ArticleDOI
01 Nov 2009
TL;DR: The results show that the protocol is energy efficient for streaming communication as well as sending short bursts of data, and thus can be used for different types of physiological signals with different sample rates.
Abstract: This paper presents an energy-efficient medium access control protocol suitable for communication in a wireless body area network for remote monitoring of physiological signals such as EEG and ECG. The protocol takes advantage of the static nature of the body area network to implement the effective time-division multiple access (TDMA) strategy with very little amount of overhead and almost no idle listening (by static, we refer to the fixed topology of the network investigated). The main goal is to develop energy-efficient and reliable communication protocol to support streaming of large amount of data. TDMA synchronization problems are discussed and solutions are presented. Equations for duty cycle calculation are also derived for power consumption and battery life predictions. The power consumption model was also validated through measurements. Our results show that the protocol is energy efficient for streaming communication as well as sending short bursts of data, and thus can be used for different types of physiological signals with different sample rates. The protocol is implemented on the analog devices ADF7020 RF transceivers.

263 citations


Patent
27 May 2009
TL;DR: In this article, the content and structure associated with each argument string are determined and a probabilistic model is trained using the determined contents and structure of each of the argument strings.
Abstract: Systems, methods, and media for detecting network anomalies are provided. In some embodiments, a training dataset of communication protocol messages having argument strings is received. The content and structure associated with each of the argument strings is determined and a probabilistic model is trained using the determined content and structure of each of the argument strings. A communication protocol message having an argument string that is transmitted from a first processor to a second processor across a computer network is received. The received communication protocol message is compared to the probabilistic model and then it is determined whether the communication protocol message is anomalous.

239 citations


Journal ArticleDOI
F. Leens1
TL;DR: Today, at the low end of the communication protocols the authors find the inter-integrated circuit (I2C) and the serial peripheral interface (SPI) protocols, which are well suited for communications between integrated circuits for slow communication with on-board peripherals.
Abstract: Today, at the low end of the communication protocols we find the inter-integrated circuit (I2C) and the serial peripheral interface (SPI) protocols. Both protocols are well suited for communications between integrated circuits for slow communication with on-board peripherals. The two protocols coexist in modern digital electronics systems, and they probably will continue to compete in the future, as both I2C and SPI are actually quite complementary for this kind of communication.

224 citations


Patent
24 Mar 2009
TL;DR: In this article, the status of a multitude of objects is maintained in memory utilizing virtual state machines which contain a small amount of persistent data but which are modeled after one of a plurality of finite state machines.
Abstract: A network appliance for monitoring, diagnosing and documenting problems among a plurality of devices and processes (objects) coupled to a computer network utilizes periodic polling and collection of object-generated trap data to monitor the status of objects on the computer network. The status of a multitude of objects is maintained in memory utilizing virtual state machines which contain a small amount of persistent data but which are modeled after one of a plurality of finite state machines. The memory further maintains dependency data related to each object which identifies parent/child relationships with other objects at the same or different layers of the OSI network protocol model. A decision engine verifies through on-demand polling that a device is down. A root cause analysis module utilizes status and dependency data to locate the highest object in the parent/child relationship tree that is affected to determine the root cause of a problem. Once a problem has been verified, a “case” is opened and notification alerts may be sent out to one or more devices. A user interface allows all objects within the network to be displayed with their respective status and their respective parent/child dependency objects in various formats.

222 citations


Journal ArticleDOI
01 Sep 2009
TL;DR: An overview of the state-of-art of real-time sensor networks for industrial applications is presented and particular attention has been paid to the description of methods and instrumentation for performance measurement in this kind of architectures.
Abstract: Distributed architectures for industrial applications are a new opportunity to realize cost-effective, flexible, scalable and reliable systems. Direct interfacing of sensors and actuators to the industrial communication network improves the system performance, because process data and diagnostics can be simultaneously available to many systems and also shared on the Web. However, sensors, especially low-cost ones, cannot use standard communication protocols suitable for computers and PLCs. In fact, sensors typically require a cyclic, isochronous and hard real-time exchange of few data, whereas PCs and PLCs exchange a large amount of data with soft real-time constrains. Looking at the industrial communication systems, this separation is clearly visible: several fieldbuses have been designed for specific sensor application areas, whereas high-level industrial equipments use wired/wireless Ethernet and Internet technologies. Recently, traditional fieldbuses were replaced by Real-Time Ethernet protocols, which are ''extended'' versions of Ethernet that meet real-time operation requirements. Besides, real-time wireless sensor networking seems promising, as demonstrated by the growing research activities. In this paper, an overview of the state-of-art of real-time sensor networks for industrial applications is presented. Particular attention has been paid to the description of methods and instrumentation for performance measurement in this kind of architectures.

211 citations


Journal ArticleDOI
TL;DR: This article introduces three distributed network scenarios that differ in the amount of cooperation between nodes and presents coherent relaying solutions that offer a distributed spatial multiplexing gain even for single-antenna nodes.
Abstract: In this article we review an important class of wireless cooperation protocols known as amplify-and-forward relaying. One or more low-complexity relay nodes assist the communication between sources and destinations without having to decode the signal. This makes AF relaying transparent to modulation and coding of the source/destination communication protocol. It is therefore a highly flexible technology that also qualifies for application in heterogeneous networks comprising many nodes of different complexity or even standards. Recently, two-way relaying was introduced, which is readily combined with AF relaying. It is a spectrally efficient protocol that allows for bidirectional communication between sources and destinations. In order to investigate the potential of wireless AF relaying, we introduce three distributed network scenarios that differ in the amount of cooperation between nodes. New challenges arise in those networks, and we discuss approaches to overcome them. For the most general case of a completely distributed system, we present coherent relaying solutions that offer a distributed spatial multiplexing gain even for single-antenna nodes. Based on real-world experiments, we validate the feasibility of all schemes in our laboratory.

175 citations


Journal ArticleDOI
TL;DR: The security of the SASI protocol is analyzed, a recently proposed ultralightweight RFID protocol with better claimed security than earlier protocols, and it is shown that SASI does not achieve resistance to tracking, which is one of its design objectives.
Abstract: Since RFID tags are ubiquitous and at times even oblivious to the human user, all modern RFID protocols are designed to resist tracking so that the location privacy of the human RFID user is not violated. Another design criterion for RFIDs is the low computational effort required for tags, in view that most tags are passive devices that derive power from an RFID reader's signals. Along this vein, a class of ultralightweight RFID authentication protocols has been designed, which uses only the most basic bitwise and arithmetic operations like exclusive-OR, OR, addition, rotation, and so forth. In this paper, we analyze the security of the SASI protocol, a recently proposed ultralightweight RFID protocol with better claimed security than earlier protocols. We show that SASI does not achieve resistance to tracking, which is one of its design objectives.

Journal IssueDOI
01 Dec 2009
TL;DR: The specific requirements and design trade-offs of a typical wireless sensor MAC protocol are outlined by describing the properties of WSN that affect the design of MAC layer protocols and a typical collection of MAC protocols presented in the literature are surveyed, classified, and described.
Abstract: Power management is an important issue in wireless sensor networks (WSNs) because wireless sensor nodes are usually battery powered, and an efficient use of the available battery power becomes an important concern specially for those applications where the system is expected to operate for long durations. This necessity for energy efficient operation of a WSN has prompted the development of new protocols in all layers of the communication stack. Provided that, the radio transceiver is the most power consuming component of a typical sensor node, large gains can be achieved at the link layer where the medium access control (MAC) protocol controls the usage of the radio transceiver unit. MAC protocols for sensor networks differ greatly from typical wireless networks access protocols in many issues. MAC protocols for sensor networks must have built-in power conservation, mobility management, and failure recovery strategies. Furthermore, sensor MAC protocols should make performance trade-off between latency and throughput for a reduction in energy consumption to maximize the lifetime of the network. This is in general achieved through duty cycling the radio transceiver. Many MAC protocols with different objectives were proposed for wireless sensor networks in the literature. Most of these protocols take into account the energy efficiency as a main objective. There is much more innovative work should be done at the MAC layer to address the hard unsolved problems. In this paper, we first outline and discuss the specific requirements and design trade-offs of a typical wireless sensor MAC protocol by describing the properties of WSN that affect the design of MAC layer protocols. Then, a typical collection of wireless sensor MAC protocols presented in the literature are surveyed, classified, and described emphasizing their advantages and disadvantages whenever possible. Finally, we present research directions and identify open issues for future medium access research. Copyright © 2009 John Wiley & Sons, Ltd.

Journal ArticleDOI
TL;DR: This paper formally investigates the scheduling problem for the dynamic segment (DS) of FlexRay and proposes a reservation-based scheduling approach that preserves the flexible medium access of the DS.
Abstract: In recent years, time-triggered communication protocols have been developed to support time-critical applications for in-vehicle communication. In this respect, the FlexRay protocol is likely to become the de facto standard. In this paper, we investigate the scheduling problem of periodic signals in the static segment of FlexRay. We identify and solve two subproblems and introduce associated performance metrics: (1) The signals have to be packed into equal-size messages to obey the restrictions of the FlexRay protocol, while using as little bandwidth as possible. To this end, we formulate a nonlinear integer programming (NIP) problem to maximize bandwidth utilization. Furthermore, we employ the restrictions of the FlexRay protocol to decompose the NIP and compute the optimal message set efficiently. (2) A message schedule has to be determined such that the periodic messages are transmitted with minimum jitter. For this purpose, we propose an appropriate software architecture and derive an integer linear programming (ILP) problem that both minimizes the jitter and the bandwidth allocation. A case study based on a benchmark signal set illustrates our results.

Proceedings ArticleDOI
15 Mar 2009
TL;DR: An overview of the current status of communication networks for substations using IEC 61850 is provided, and the possible future trends for extending the scope of the standard and using its capabilities for other applications within the distribution system are discussed.
Abstract: Minimizing implementation time and manual configuration, as well as straightforward upgradability are the key requirements of efficient substation automation systems. For larger utilities this often necessitates achieving interoperability between different devices from multiple vendors. Since the early 1990's it was noticed that the speed of advances in communication technology seemed to overpass its power system counterpart, which called for more adaptability by substation automation systems and higher independence from the underlying communication technology. The natural shift in the industry from proprietary communication protocols to open access standards was therefore further accelerated and was directed towards more advanced solutions that provide an interoperable and future proof environment. In order to be able to respond to these concerns, IEC 61850 was proposed as a future proof, adaptable communication protocol, capable of providing interoperability in a multi-vendor environment and with a highly advanced object oriented modeling structure. The migration from legacy protocols and de facto standards such as Modbus, DNP3, and IEC 60870-5 has already started and it seems likely that it will continue at a steady pace in the future. In addition to the efforts to provide an advanced solution for substation automation systems, there is also a need for extending the “automation” benefits to beyond the substations either downstream, at the feeder level or upstream, at a higher level of network management. The objective of this paper is to provide an overview of the current status of communication networks for substations using IEC 61850, and also discuss the possible future trends for extending the scope of the standard and using its capabilities for other applications within the distribution system.

Journal ArticleDOI
TL;DR: A way of combining retransmissions with real-time worst-case scheduling analysis is presented that can offer both a high grade of reliability and hard real- time support in industrial applications with strict reliability and timing requirements.
Abstract: Increased mobility coupled with a possible reduction of cabling costs and deployment time makes wireless communication an attractive alternative for the automation industry and related application areas. Methods compensating for the high probability of bit errors accompanying wireless transmissions are, however, needed. This is predominantly important in industrial applications with strict reliability and timing requirements, which cannot be met by standard communication protocols as, e.g., TCP. In this paper, a way of combining retransmissions with real-time worst-case scheduling analysis is presented that can offer both a high grade of reliability and hard real-time support. The presented solution handles one or several retransmission attempts of erroneous data without jeopardizing already guaranteed delay bounds of other packets. A real-time analysis for a full-duplex, asymmetric link, utilizing the novel retransmission scheme and supporting both piggybacked and nonpiggybacked acknowledgments, is provided. A simulation study is presented that evaluates the performance of the retransmission scheme for bit-error rates typically experienced in wireless communication. The results clearly indicate a possible reduction of the message error rate by several orders of magnitude.

Journal ArticleDOI
TL;DR: An analytical model is developed to evaluate the performance of MCTRP in terms of the average full ring delay, emergency message delay, and ring throughput, and the efficiency and effectiveness of the proposed MCT RP are demonstrated.
Abstract: This paper proposes a multi-channel token ring media access control (MAC) protocol (MCTRP) for inter-vehicle communications (IVC). Through adaptive ring coordination and channel scheduling, vehicles are autonomously organized into multiple rings operating on different service channels. Based on the multi-channel ring structure, emergency messages can be disseminated with a low delay. With the token based data exchange protocol, the network throughput is further improved for non-safety multimedia applications. An analytical model is developed to evaluate the performance of MCTRP in terms of the average full ring delay, emergency message delay, and ring throughput. Extensive simulations with ns-2 are conducted to validate the analytical model and demonstrate the efficiency and effectiveness of the proposed MCTRP.

Proceedings ArticleDOI
16 Aug 2009
TL;DR: It is argued that wireless protocols can exploit simultaneous transmission to reduce the cost of reliable multicast by orders of magnitude and be extended to solve group communication problems and the challenges inherent to build innovative protocols which are faster and reliable at the same time.
Abstract: Network protocol designers, both at the physical and network level, have long considered interference and simultaneous transmission in wireless protocols as a problem to be avoided. This, coupled with a tendency to emulate wired network protocols in the wireless domain, has led to artificial limitations in wireless networks.In this paper, we argue that wireless protocols can exploit simultaneous transmission to reduce the cost of reliable multicast by orders of magnitude. With an appropriate application interface, simultaneous transmission can also greatly speed up common group communication primitives, such as anycast, broadcast, leader election and others.The proposed method precisely fits into the domain of directly reachable nodes where many group communication mechanisms are commonly used in routing protocols and other physical-layer mechanisms. We demonstrate how simultaneous transmission can be used to implement a reliable broadcast for an infrastructure and peer-to-peer network using a prototype reconfigurable hardware. We also validate the notion of using simple spectrum sensing techniques to distinguish multiple transmissions. We then describe how the mechanism can be extended to solve group communication problems and the challenges inherent to build innovative protocols which are faster and reliable at the same time.

Journal ArticleDOI
TL;DR: This paper proposes a general framework based on the principles of epidemic theory, for vulnerability analysis of current broadcast protocols in wireless sensor networks, and develops a common mathematical model for the propagation that incorporates important parameters derived from the communication patterns of the protocol under test.
Abstract: While multi-hop broadcast protocols, such as Trickle, Deluge and MNP, have gained tremendous popularity as a means for fast and convenient propagation of data/code in large scale wireless sensor networks, they can, unfortunately, serve as potential platforms for virus spreading if the security is breached. To understand the vulnerability of such protocols and design defense mechanisms against piggy-backed virus attacks, it is critical to investigate the propagation process of these protocols in terms of their speed and reachability. In this paper, we propose a general framework based on the principles of epidemic theory, for vulnerability analysis of current broadcast protocols in wireless sensor networks. In particular, we develop a common mathematical model for the propagation that incorporates important parameters derived from the communication patterns of the protocol under test. Based on this model, we analyze the propagation rate and the extent of spread of a malware over typical broadcast protocols proposed in the literature. The overall result is an approximate but convenient tool to characterize a broadcast protocol in terms of its vulnerability to malware propagation. We have also performed extensive simulations which have validated our model.

Proceedings ArticleDOI
23 Jun 2009
TL;DR: Existing WMSN hardware and communication protocol layer technologies for achieving or fulfilling the objectives of WMSN are surveyed.
Abstract: Wireless Multimedia Sensor Networks (WMSNs) is comprised of small embedded video motes capable of extracting the surrounding environmental information, locally processing it and then wirelessly transmitting it to parent node or sink. It is comprised of video sensor, digital signal processing unit and digital radio interface. In this paper we have surveyed existing WMSN hardware and communication protocol layer technologies for achieving or fulfilling the objectives of WMSN. We have also listed the various technical challenges posed by this technology while discussing the communication protocol layer technologies. Sensor networking capabilities are urgently required for some of our most important scientific and societal problems like understanding the international carbon budget, monitoring water resources, monitoring vehicle emissions and safeguarding public health. This is a daunting research challenge requiring distributed sensor systems operating in complex environments while providing assurance of reliable and accurate sensing.

Proceedings ArticleDOI
11 May 2009
TL;DR: The Inter-Module Communication protocol is presented, a message-oriented protocol designed and implemented in the Underwater Systems and Technology Laboratory (LSTS) to build interconnected systems of vehicles, sensors and human operators that are able to pursue common goals cooperatively by exchanging real-time information about the environment and updated objectives.
Abstract: This paper presents the Inter-Module Communication (IMC) protocol, a message-oriented protocol designed and implemented in the Underwater Systems and Technology Laboratory (LSTS) to build interconnected systems of vehicles, sensors and human operators that are able to pursue common goals cooperatively by exchanging real-time information about the environment and updated objectives. IMC abstracts hardware and communication heterogeniety by providing a shared set of messages that can be serialized and transferred over different means.

Proceedings ArticleDOI
26 May 2009
TL;DR: The implementation and analysis of the testbed considering the Link Quality Window Size (LQWS) parameter of Optimized Link State Routing (OLSR) and Better Approach To Mobile Ad-hoc Networking (B.T.A.M.N.) protocols found that throughput of TCP was improved by reducing LQWS.
Abstract: In this paper, we present the implementation and analysis of our testbed considering the Link Quality Window Size (LQWS) parameter of Optimized Link State Routing (OLSR) and Better Approach To Mobile Ad-hoc Networking (B.A.T.M.A.N.) protocols. We investigate the effect of mobility in the throughput of a Mobile Ad-hoc Network (MANET). The mobile nodes move toward the destination at a regular speed. When the mobile nodes arrive at the corner, they stop for about three seconds. In our experiments, we consider two cases: only one node is moving (mobile node)and two nodes (intermediate nodes) are moving at the same time. We assess the performance of our testbed in terms of throughput, round trip time, jitter and packet loss. From our experiments, we found that throughput of TCP was improved by reducing LQWS.

Proceedings ArticleDOI
28 Dec 2009
TL;DR: An extensive comparative simulation study of some well-known link quality estimators using TOSSIM to understand the statistical behavior of LQE techniques, helping system designers choose the most appropriate for their network protocol architectures.
Abstract: Link quality estimation (LQE) in wireless sensor networks (WSNs) is a fundamental building block for an efficient and cross-layer design of higher layer network protocols. Several link quality estimators have been reported in the literature; however, none has been thoroughly evaluated. There is thus a need for a comparative study of these estimators as well as the assessment of their impact on higher layer protocols. In this paper, we perform an extensive comparative simulation study of some well-known link quality estimators using TOSSIM. We first analyze the statistical properties of the link quality estimators independently of higher-layer protocols, then we investigate their impact on the Collection Tree Routing Protocol (CTP). This work is a fundamental step to understand the statistical behavior of LQE techniques, helping system designers choose the most appropriate for their network protocol architectures.

Book ChapterDOI
01 Jan 2009
TL;DR: It is concluded that the FlexRay protocol lacks sufficient protection against the executed attacks, and it is argued that future versions of the specification should include security protection.
Abstract: The automotive industry has over the last decade gradually replaced mechanical parts with electronics and software solutions. Modern vehicles contain a number of electronic control units (ECUs), which are connected in an in-vehicle network and provide various vehicle functionalities. The next generation automotive network communications protocol FlexRay has been developed to meet the future demands of automotive networking and can replace the existing CAN protocol. Moreover, the upcoming trend of ubiquitous vehicle communication in terms of vehicle-to-vehicle and vehicle-to-infrastructure communication introduces an entry point to the previously isolated in-vehicle network. Consequently, the in-vehicle network is exposed to a whole new range of threats known as cyber attacks. In this paper, we have analyzed the FlexRay protocol specification and evaluated the ability of the FlexRay protocol to withstand cyber attacks. We have simulated a set of plausible attacks targeting the ECUs on a FlexRay bus. From the results, we conclude that the FlexRay protocol lacks sufficient protection against the executed attacks, and we therefore argue that future versions of the specification should include security protection.

Patent
26 Feb 2009
TL;DR: In this article, an efficient frequency assignment for mobile terminals in coexisting wireless communication systems is described, and two prioritized lists are defined, a first list comprising a first entry relating to the macro communication system and the second entry referring to the localized communication system, the first and second entries each listing at least one common frequency.
Abstract: Efficient frequency assignment for mobile terminals in coexisting wireless communication systems is described herein The coexisting wireless communication systems comprise a macro communication system and a localized communication system Two prioritized lists are defined, a first list comprising a first entry relating to the macro communication system and the second entry relating to the localized communication system, the first and second entries each listing at least one common frequency Based on the first list, a mobile terminal uses communication protocols associated with the localized communication system

Journal ArticleDOI
TL;DR: This study comprehensively analyzes IEEE 802.15.4 duty-cycle operation and develops a novel analytical model that accommodates a general traffic distribution that can be used as guidelines for future low-power ZigBee network deployment.
Abstract: ZigBee, a unique communication standard designed for low-rate wireless personal area networks, has extremely low complexity, cost, and power consumption for wireless connectivity of inexpensive, portable, and moving devices. ZigBee uses the IEEE 802.15.4 standard as its communication protocol for medium access control (MAC) layer and physical (PHY) layer. The IEEE 802.15.4 MAC layer achieves duty-cycle operations by setting two system parameters, macBeaconOrder (BO) and macSuperFrameOrder (SO), to achieve low power consumption for ZigBee devices. This study comprehensively analyzes IEEE 802.15.4 duty-cycle operation. Specifically, a novel analytical model that accommodates a general traffic distribution is developed. An NS-2 based simulation model, which is validated by the developed analytical model is also proposed. Through the experiments conducted by the analytical and simulation models, some important performance-evaluation insights are gained that can be used as guidelines for future low-power ZigBee network deployment.

Journal ArticleDOI
TL;DR: This paper identifies two general frameworks (inter-flow and intra-flow) that encompass several network coding-based systems proposed in wireless networks and reveals vulnerabilities to a wide range of attacks, which may severely degrade system performance.

Patent
31 Mar 2009
TL;DR: In this paper, a system and method is disclosed for receiving a network event in a network format, mapping the network event into a format expected by a central monitoring system, and communicating the mapped network event to the central monitoring systems.
Abstract: A system and method is disclosed for receiving a network event in a network format, mapping the network event into a format expected by a central monitoring system, and communicating the mapped network event to the central monitoring system. The system may employ a variety of communication protocols and physical architectures. The system may include an access controller that may connect a plurality of intelligent electronic devices and may be the primary interface with an information system or central monitoring system. The access controller may include a programmable logic engine in compliance with the IEC-61131-3 standard. The access controller may further be configured to implement rules designed to govern actions taken as a result of network information.

Patent
24 Sep 2009
TL;DR: In this article, a Near Field Communications (NFC) circuit is connected to the processor for communicating using an NFC communications protocol, and a magnetic sensor is supported by the housing and connected to a processor for sensing a magnetic field and generating a signal to the receiver.
Abstract: A mobile wireless communications device includes a housing and a circuit board carried by the housing. Radio frequency (RF) circuitry and a processor are carried by the housing and operative with each other. A Near Field Communications (NFC) circuit is connected to the processor for communicating using an NFC communications protocol. A magnetic sensor is supported by the housing and connected to the processor for sensing a magnetic field and generating a signal to the processor and in response, the processor activating the NFC circuit for transmitting or receiving data using the NFC communications protocol.

Book ChapterDOI
11 Feb 2009
TL;DR: Extensive simulation results demonstrate that MCRT can effectively utilize multiple channels to reduce the number of deadlines missed in end-to-end communications and outperforms a state-of-the-art real-time protocol and two baseline multi-channel communication schemes.
Abstract: As many radio chips used in today's sensor mote hardware can work at different frequencies, several multi-channel communication protocols have recently been proposed to improve network throughput and reduce packet loss for wireless sensor networks. However, existing work cannot utilize multiple channels to provide explicit guarantees for application-specified end-to-end communication delays, which are critical to many real-time applications such as surveillance and disaster response. In this paper, we propose MCRT, a multi-channel real-time communication protocol that features a flow-based channel allocation strategy. Because of the small number of orthogonal channels available in current mote hardware, MCRT allocates channels to network partitions formed based on many-to-one data flows. To achieve bounded end-to-end communication delay for every data flow, the channel allocation problem has been formulated as a constrained optimization problem and proved to be NP-complete. We then present the design of MCRT, which includes a channel allocation algorithm and a real-time packet forwarding strategy. Extensive simulation results based on a realistic radio model demonstrate that MCRT can effectively utilize multiple channels to reduce the number of deadlines missed in end-to-end communications. Our results also show that MCRT outperforms a state-of-the-art real-time protocol and two baseline multi-channel communication schemes.

01 Jul 2009
TL;DR: This document provides application-specific requirements and the PCEP extensions in support of a global concurrent optimization (GCO) application.
Abstract: The Path Computation Element (PCE) is a network component, application, or node that is capable of performing path computations at the request of Path Computation Clients (PCCs). The PCE is applied in Multiprotocol Label Switching Traffic Engineering (MPLS-TE) networks and in Generalized MPLS (GMPLS) networks to determine the routes of Label Switched Paths (LSPs) through the network. The Path Computation Element Communication Protocol (PCEP) is specified for communications between PCCs and PCEs, and between cooperating PCEs. When computing or re-optimizing the routes of a set of LSPs through a network it may be advantageous to perform bulk path computations in order to avoid blocking problems and to achieve more optimal network- wide solutions. Such bulk optimization is termed Global Concurrent Optimization (GCO). A Global Concurrent Optimization is able to simultaneously consider the entire topology of the network and the complete set of existing LSPs, and their respective constraints, and look to optimize or re-optimize the entire network to satisfy all constraints for all LSPs. The Global Concurrent Optimization (GCO) application is primarily an NMS based solution. This document provides application-specific requirements and the PCEP extensions in support of a global concurrent optimization (GCO) application.